The point here is that the "mandatory helmet" part is less significant than the "law enforcement" part. People who would happily be riding with a helmet are di

The point here is that the "mandatory helmet" part is less significant than the "law enforcement" part. People who would happily be riding with a helmet are disincentivized to go riding at all, because they don't want to be the subject of police patrol. That's the effect we clearly don't want.